It is frequently desired to provide receptacles, such as bottles and ampoules, which contain sterile liquids, and which can be re-used. Unit dose containers can be provided, but these can be relatively expensive to produce in large numbers, and also bulky and inconvenient to use, especially when multiple doses are required.
It is known in the art to provide bottles containing sterile liquids, a rubber septum covering the neck of the bottle. To extract the desired amount of liquid, a needle is inserted into the container, and liquid extracted through the needle. When the desired amount of liquid has been removed, the needle is withdrawn, and the rubber reseals the small hole that is left.
Multi-use containers are generally made of glass, while single dose containers are typically made of a flexible plastics material which collapses on extraction of the liquid, rather than causing air to be sucked back in, or leaving a vacuum. The neck of such receptacles needs to be relatively solid, to prevent the collapse of this part of the receptacle.
In either case, the result is that the rubber septum needs to be made of a different material from the bottle, and must be positioned during manufacture, requiring expensive and complicated apparatus.
Alternatives have been sought, and one such alternative involves a blow-fill-seal bottle or ampoule, wherein a cap can fit over the neck. The cap is fitted with a piercing device, so that when the cap is forcibly positioned over the neck of the ampoule, the ampoule is pierced.
The problem with the above construction is that blow-fill-seal ampoules are necessarily made using two substantially similar moulds, thereby leaving a seam around the bottle or ampoule which will be centrally placed on the neck. The piercing point is placed in the centre of the cap for effectiveness and, so, will have to pierce the seam which could then split, for example. However, the most undesirable aspect of this construct is that the seam extends all of the way around the ampoule, so that not only does the piercing point have to pierce the seam, but the cap also has to fit over the seam in at least two places. The problem is that, in blow-fill-seal constructions, the seam tends to stand proud of the ampoule, so that leakage from the cap at the seams of the bottle is difficult or impossible to prevent.
The problem has been addressed, and a further construct is known which effectively reduces the possibility of leakage by duplicating the mating arrangement of the cap with the ampoule. Thus, at the top of the neck of the ampoule, there is a nipple. The cap is so designed that an inner cap fits tightly over the nipple, while the outer cap screws down over the neck. Within the inner cap is the piercing portion. Any leakage is thereby substantially limited to within the inner cap, although leakage is still observed into the outer cap, and occasionally beyond.